The 2011 uprisings that swept across the Middle East and North Africa led some countries into internal conflicts that brought about major social and political changes with large regional repercussions. Libya is a case in point, where a forty-two year-long dictatorial regime was toppled and a democratic transition drifted into a civil war in just three years. If the country’s internal instability and its regional repercussions were not enough to raise concerns, European countries can no longer ignore the continuous increase of migrants to Europe and the dramatic increase in the presence of ISiS fighters along the Libyan coast. How did we get to this point? And how do we help Libya recover peace and stability? This paper looks at the challenges and responsibilities of regional and international actors that have intervened in Libya during and after the 2011 conflict. In particular, it looks at the nature and impact of the military interventions during the 2011 Libyan revolution and at the inadequate State-building efforts deployed since then. It shows how the international intervention in the Libyan conflict and its aftermaths was partisan, fragmented, suffered from competing goals and was ill-designed to address the large post-conflict challenges facing the country. Confronted with a regional proxy war playing out in Libya and with challenges far exceeding their size and mandate, international missions could not prevent Libya from sliding towards a civil war, the penetration of ISIS, the emergence of Islamic extremism and the explosion of illicit trade of arms, drugs and human beings. These failures highlight the importance of two central principles for the success of international efforts to achieve peace and security: comprehensiveness and multilateralism. A comprehensive strategy entails looking at a conflict and at the role that international actors ought to play, both vertically – across time, and horizontally – across dimensions. Multilateralism instead calls for an institutionalized coordination of the actions of all major stakeholders in accordance with a set of agreed-upon principles that restrain the pursuit of immediate and individual goals to the benefit of long-run, collective interests. This paper provides a critical contribution to the scholarly research on the role of international actors in domestic conflicts and democratic transitions. Furthermore, it offers invaluable lessons for states and international organizations aiming at maintaining peace and security in the region.